کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10244777 | 47702 | 2005 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Catalytic sites in silica-supported titanium catalysts: silsesquioxane complexes as models
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The number of SiOTi bonds in silica-supported titanium catalysts is an important parameter that affects activity and selectivity. Although comparisons between different catalysts can be made by infrared spectroscopy, estimation of the contribution of the different species is a difficult task. UV spectroscopy has been used to characterize three different titanium-silsesquioxane complexes. The wavelength in solution is highly dependent on the concentration, and broad bands are obtained by DRUV, at wavelengths that correlate with the number of SiOTi bonds. The deconvolution of the DRUV spectra of silica-supported titanium catalysts allows identification of the three types of tetrahedral (pentacoordinated) species, together with octahedral species. These results correlate well with the known silanol densities of the different silica supports, and the catalytic activity and selectivity for epoxidation are clearly favored by the reduction in octahedral titanium and the increase in the number of tripodal species.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Catalysis - Volume 233, Issue 1, 1 July 2005, Pages 90-99
Journal: Journal of Catalysis - Volume 233, Issue 1, 1 July 2005, Pages 90-99
نویسندگان
José M. Fraile, José I. GarcÃa, José A. Mayoral, Eugenio Vispe,